AICAR and metformin, but not exercise, increase muscle glucose transport through AMPK-, ERK-, and PDK1-dependent activation of atypical PKC

Sajan, M P; Bandyopadhyay, G; Miura, A; Standaert, M L; Nimal, S; Longnus, S L; Van Obberghen, E; Hainault, I; Foufelle, F; Kahn, R; Braun, U; Leitges, M; Farese, R V (2010). AICAR and metformin, but not exercise, increase muscle glucose transport through AMPK-, ERK-, and PDK1-dependent activation of atypical PKC. American journal of physiology - endocrinology and metabolism, 298(2), E179-92. Bethesda, Md.: American Physiological Society 10.1152/ajpendo.00392.2009

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Activators of 5'-AMP-activated protein kinase (AMPK) 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR), metformin, and exercise activate atypical protein kinase C (aPKC) and ERK and stimulate glucose transport in muscle by uncertain mechanisms. Here, in cultured L6 myotubes: AICAR- and metformin-induced activation of AMPK was required for activation of aPKC and ERK; aPKC activation involved and required phosphoinositide-dependent kinase 1 (PDK1) phosphorylation of Thr410-PKC-zeta; aPKC Thr410 phosphorylation and activation also required MEK1-dependent ERK; and glucose transport effects of AICAR and metformin were inhibited by expression of dominant-negative AMPK, kinase-inactive PDK1, MEK1 inhibitors, kinase-inactive PKC-zeta, and RNA interference (RNAi)-mediated knockdown of PKC-zeta. In mice, muscle-specific aPKC (PKC-lambda) depletion by conditional gene targeting impaired AICAR-stimulated glucose disposal and stimulatory effects of both AICAR and metformin on 2-deoxyglucose/glucose uptake in muscle in vivo and AICAR stimulation of 2-[(3)H]deoxyglucose uptake in isolated extensor digitorum longus muscle; however, AMPK activation was unimpaired. In marked contrast to AICAR and metformin, treadmill exercise-induced stimulation of 2-deoxyglucose/glucose uptake was not inhibited in aPKC-knockout mice. Finally, in intact rodents, AICAR and metformin activated aPKC in muscle, but not in liver, despite activating AMPK in both tissues. The findings demonstrate that in muscle AICAR and metformin activate aPKC via sequential activation of AMPK, ERK, and PDK1 and the AMPK/ERK/PDK1/aPKC pathway is required for metformin- and AICAR-stimulated increases in glucose transport. On the other hand, although aPKC is activated by treadmill exercise, this activation is not required for exercise-induced increases in glucose transport, and therefore may be a redundant mechanism.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Cardiovascular Disorders (DHGE) > Clinic of Heart Surgery
UniBE Contributor:	Henning Longnus, Sarah
ISSN:	0193-1849
Publisher:	American Physiological Society
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:13
Last Modified:	27 Feb 2024 14:29
Publisher DOI:	10.1152/ajpendo.00392.2009
PubMed ID:	19887597
Web of Science ID:	000273695500005
URI:	https://boris.unibe.ch/id/eprint/2773 (FactScience: 205647)